制备了结构为ITO/PEDOT∶PSS/polyvinylcarbazole (PVK)/carbon quantum dots(CDs)/LiF/Al的电致发光器件。器件的发光光谱显示: 在电压从7 V增大到13 V的过程中, 光谱峰值从380 nm移动到520 nm, 色坐标由(0.20,0.20)移动到(0.29,0.35)。经与PL光谱对比认为, EL光谱包含了PVK与碳量子点的双重贡献, 随着电压的增大, 碳量子点的发射逐渐增强, PVK发光先增强后减弱。结合器件能级结构讨论了器件的发光机制, 认为低电场下的PVK兼具发光层和电子阻挡层的功能, EL光谱为PVK层和碳量子点的发光叠加; 随着电场强度的增大, 碳量子点和PVK界面区的空间电荷阻止了电子向PVK的传输, 光谱转变为由碳量子点和激基复合物的共同贡献。

The electroluminescent devices with the structure of ITO/PEDOT∶PSS/polyvinylcarbazole (PVK)/carbon quantum dots(CDs)/LiF/Al were fabricated. When the voltage raises from 7 V to 13 V, the voltage-dependent EL spectra can be observed to shift from 380 nm to 520 nm, and the color coordinates shift from (0.20, 0.20) to (0.29, 0.35). The device operating mechanism is investigated based on PL spectra of PVK and CDs and device energy-level diagram. PVK layer is considered to be responsible for electron blocking and meanwhile the emission in low electric field. The EL spectra are proposed to be the overlapping of PVK and CDs and their interface. With the voltage increase, the emission intensity of CDs displays enhancement but the converse trend is observed for PVK. Under high field, electroplex emission at PVK/CDs interface is known to contributed to whole EL spectra combining with CDs emission.